Brake disc of carbon-carbon composite material

Abstract

A brake disc of carbon-carbon composite material comprising a substrate of a mixture of carbon fibres of two very different ranges of length and embedded in a carbon matrix. The longer fibres are oriented and distributed randomly in planes approximately parallel to the friction surfaces of the disc, and the shorter fibres are oriented and distributed randomly in the volume of the disc. The brake discs according to the invention are useful in particular in the aviation field. They can be made by ultrasonically molding a mixture of the fibres and a suitable liquid, followed by heat treatment; or by chemical deposition of carbon from the vapor phase.

We claim: 
     
       1. A brake disc of carbon-carbon composite material and having friction faces, comprising a substrate of a mixture of short carbon fibres of two very different length ranges embedded in a carbon matrix, in which the longer fibres are oriented and distributed randomly in planes approximately parallel to the friction faces of the disc and the shorter fibres are oriented and distributed randomly in the volume of the disc. 
     
     
       2. A brake disc according to claim 1, in which the carbon fibres are of graphite. 
     
     
       3. A brake disc according to claim 1, in which the length of the longer fibres is in the range 4 to 6 cm and the length of the shorter fibres is in the range 0.015 to 0.3 cm. 
     
     
       4. A brake disc according to claim 1, in which the carbon fibres are produced from a pitch or tar precursor. 
     
     
       5. A brake disc according to claim 1, in which the carbon fibres are produced from a polyacrylonitrile precursor.